The invention relates broadly to a plug for temporarily plugging off a well casing. More specifically, the invention covers a packer-type bridge plug, which is retrievable from the well casing.
In the production of oil and gas there are various downhole operations which may require temporarily plugging off the well casing at a given point, or at more than one point. Examples of such operations are cementing of the annulus between the borehole and the well casing, hydraulic fracturing of a producing zone, or treating the zone with chemicals to consolidate loose sand.
The tools now available for plugging the well casing are not entirely satisfactory in that they are difficult to use and costly to maintain. For example, one of the commercially available plugging tools has an extremely complex structure which includes many parts. The complex structure and the number of parts makes it easy to overlook a defective part during reconditioning of the tool between operations. This same tool is built with a substantial number of O-ring seals, which adds to the problem of fluid leakage in a downhole tool.